The present invention relates to a mooring device comprising a floating device, such as a vessel, said floating device supporting a rotatable body, such as a turntable or turret, which body is rotatable about a vertical axis and has means for connecting thereto anchor lines which according to catenary lines extend in different directions to anchors at the bottom of the body of water.
The prior art knows a plurality of mooring devices of this type. Examples are found in U.S. Pat. No. 4,650,431 or U.S. Pat. No. 4,580,986.
The floating device or vessel usually is a tanker and from said tanker extends at least one hose towards a swivel above the turntable or turret and from said swivel at least one hose extends through the turntable or turret towards the bottom of the body of water where said hose is connected to a well or a pipe line. The anchor lines keep the vessel in place and allow displacement of the vessel under the influence of wind, waves and currents against a restoring force which is generated by the anchor lines. The anchor line or lines which extend away from the direction in which the vessel is displaced are more or less tightened during displacement or in other words function as a spring which rapidly becomes more and more rigid. Under normal weather conditions including storms this forms no problem.
However, if an exceptionally heavy storm occurs, such as the type of storm which statistically occurs only once in a century, or during typhons, then the loads on anchor lines and vessel exceed a permissible maximum.